This invention relates to a novel method for polymerizing olefins using acetylenes as coinitiators and, more particularly, in combination with tungsten salts such as tungsten hexachloride.
The olefin metathesis reaction is indicated by equations (1) and (2) below: ##STR1##
This reaction interconverts olefins that are acyclic as shown in equation (1) and polymerizes those that are cyclic as shown in equation (2). It is commonly brought about by combining tungsten hexachloride with ethylaluminum dichloride and often ethanol as well, although a number of other derivatives of tungsten, molybdenum, rhenium, and other metals have been substituted for the tungsten hexachloride and assorted derivatives of aluminum, tin, or other elements have been substituted for ethylaluminum dichloride.
U.S. Pat. No. 4,334,048, issued to Katz et al., which is incorporated herein by reference, describes procedures for effecting olefin metathesis in which acetylenes are substituted for the organoaluminum halide or related coinitiators. The other component of the initiating mixture in that process was (phenylmethoxycarbene)pentacarbonyltungsten. It would be desirable if acetylenes could be used in place of the organoaluminum halide (or related coinitiators) in combination with tungsten hexachloride instead of phenylmethoxycarbene)pentacarbonyltungsten. The advantage of using tungsten hexachloride instead of (phenylmethoxycarbene)pentacarbonyltungsten is its easy availability and the fact that in combination with ethanol and ethylaluminum dichloride, the reaction proceeds much faster than it does when the combination of (phyenylmethoxycarbene)pentacarbonyltungsten and an acetylene is used. It is thus desirable to use the acetylenes in combination with some readily available salts as coinitiators to bring about the olefin metathesis.